1. Field of the Invention
The present invention relates to a sheet processing apparatus and, more particularly, to a sheet processing apparatus having a sheet buffer function.
2. Description of the Related Art
In recent years, in some image forming apparatus, a sheet processing apparatus is set adjacent to a paper discharge unit of an image forming apparatus main body in order to perform finishing for sheets after image formation such as sorting of the sheets or stapling the sheets.
The sheet processing apparatus has plural means for conveying a sheet, which is conveyed from the image forming apparatus, to a paper discharge tray and discharging the sheet. The means are roughly divided into a conveying path for not performing the finishing and a conveying path for performing the finishing. When the finishing is not performed, the sheet is conveyed through the conveying path for not performing the finishing and directly discharged onto the paper discharge tray. When the finishing is performed, the sheet is conveyed to a processing tray through the conveying path for performing the finishing, which is branched from the conveying path for not performing the finishing, and stacked. When a set number of sheets are stacked, the sheets are aligned on the processing tray and subjected to the finishing.
Conventionally, a sheet finishing apparatus that removes charges from sheets, which are conveyed and discharged, to satisfactorily stack the sheets has been proposed. For example, in some sheet finishing apparatus, a discharge opening as a paper discharge section for finishing is formed between a paper discharge roller and a movable sheet guide and, in a staple mode, because the movable sheet guide pivots, a charge removing brush attached to a distal end of the movable sheet guide does not disturb discharge of sheets through the discharge opening and moves to a position where charge removal for sheets, which are discharged and fall onto a staple tray with own weight thereof, can be performed (JP-A-7-48061).